The industrial use of biocatalytic reactions is rapidly growing with the advancement of biotechnology because various catalytic reactions, including reactions that have not conventionally been able to be carried out using conventional chemical catalysts, are performed under biocompatible conditions.
Such reactions are typically applied to the synthesis of chiral compounds, alcohols, aldehydes, amino acids and medical intermediates, the synthesis of polymers suitable for biodegradable or biometric applications, and the development of biosensors for assays and diagnosis. Furthermore, because of current problems attributable to an increase in the concentration of carbon dioxide and global warming resulting therefrom, thorough research into decreasing carbon dioxide emissions and producing a new type of energy through the reduction reaction of carbon dioxide is ongoing in academic and industrial fields. Specifically, carbon dioxide is converted into formic acid using a formate dehydrogenase, the produced formic acid is converted into formaldehyde by means of a formaldehyde dehydrogenase, and the formaldehyde is converted into methanol by means of an alcohol dehydrogenase. For this, the formaldehyde dehydrogenase must be essentially contained in a multi-enzyme system. Despite its potential importance and usability, there have been almost no reports on reduction reactions involving formaldehyde dehydrogenase, compared to oxidation reactions thereof. Since the oxidation reaction, rather than the reduction reaction, is carried out in a thermodynamically favorable and feasible manner due to the properties of typical dehydrogenase, formaldehyde dehydrogenase having independent reduction activity has not yet been reported.
Therefore, a novel formaldehyde dehydrogenase, having independent reducibility for converting formic acid into formaldehyde, needs to be reliably applicable to a multi-enzyme system so that methanol can be produced using carbon dioxide, and moreover, so that a variety of industrially important chemicals can be produced.